INVOLVEMENT OF FLAVONOID OXIDATION WITH CHLOROPHYLL DEGRADATION BY PEROXIDASE IN WASE SATSUMA MANDARIN FRUITS

Effects of flavonoid pigments on chlorophyll (Chl) degradation by Chl degrading peroxidase in the flavedo of Wase satsuma mandarin (Citrus u nshiu Marc. var. praecox Tanaka 'Okitsuwase') fruit were studied. Chl was degraded when hydrogen peroxide was added to a reaction mixture co ntaining Chl and a phosphate buffer extract from the flavedo. Chloroph yllide, which was formed by the action of chlorophyllase in the extrac t, was also degraded while flavonoid content decreased concomitantly. Analyses of the flavonoids with HPLC showed that hesperidin and nariru tin were the major flavedo flavonoids; the former decreased significan tly, whereas the latter showed almost no change during the Chl degrada tion reaction. In ethylene-treated fruits, flavedo hesperidin content decreased with the degreening during storage, indicating that flavonoi d oxidation by Chl degrading peroxidase could be involved in Chl degra dation.